Ammunition



Patented Apr. 25, 1933 UNITED STATES JAMES E. BURNS,

PATENT OFFICE OF BRIDGEPORT, CONNECTICUT, ASSIGNOR TO REMINGTON ARES COMPANY, INC., A CORPORATION OF DELAWARE AMMUNITIIZ-ON No Drawing.

The present invention relates to ammunition, particularly of the metallic cartridge type, and to the primers for such ammuni-' present invention, however, 1s the detrlmental efl'ectof mercury fulminate on many tion.

Cartridges embodying percussion primers for the production of a flame for ignition of the main powder charge are, in general, of two distinct types: 1. Center fire cartridges where th primer charge is contained within a cup positionedat the center of the rear face of the cartridge head, the main powder charge being reached by the flame of ignition through a flash hole; the primer charge being in contact with the primer cup only and being separated from the walls of the cartridge case and from the main powder charge. 2. Rim-fire ca rtridgeswhere the primer charge is contained within the rear portion of the head of the cartridge case and is distributedoutwardly into the rim portionin intimate contact with the shell body and with the main powder charge. Due to these physical differences between the two typesof primers and for other reasons not necessary to discuss here, priming compositions for the two types of cartridges must necessarily differ in many respects as to choice and proportions of the ingredients, methods of loading, etc; However, regardless of type, most priming niixtures heretofore have contained certain essential ingredients, among which is mercury fulminate, used in some instances as the combustion initiator for causing a flame-producing reaction between a fuel and an oxygen liberating substance. in the primer, and in other mstances as a.

sensitizer for stimulating a similar reaction when a different combustion initiator was used. Notwithstanding the fact that mercury fulminate has for many years been a standard and extensively used material for these purposes, it has many serious disadvantages. Among these disadvantages may be mentioned 1ts polsonous nature and con- Application filed September 30, 1929. Serial No. 396,415.

sequent dangers to the health of persons handling the material, and its high and increasing cost. Of more significance as regards the metals, particularly brass.

Commercial yellow brass containing approximately 60-70% copper and 40-30% zinc is particularly desirable in ammunition manufacture in the construction of cartridge cases, for reasons among others of its strength, lasting qualities, comparatively low cost, attractive appearance, and ductility enabling it to be easily worked into.

shape. It has been used quite universally in the manufacture of cartridge cases for cen- I ter-fire ammunition not only in small arms cartridges, but in cartridge cases for larger minor calibre ordnance.

It is a material which is neither too soft nor too hardand which possesses the necessary strength and elasticity to successfully withstand the expansion due to the pressure of the gasesin the barrel chamber without injury to the cartridge case, thereby enabling easy extraction from the chamber and repeated reloading and use of the case.

The use of brass in contact with priming mixtures which include mercury fulminate is quite impracticable. Mercury amalgamates freelywith zinc, and when brass and 'fulminate of mercury are brought in contact with each other the zinc of the brass is attacked, causing deterioration and breakdown of the brass, as well as destruction of the priming mixture. In brass cased centerfire ammunition the difliculty has been partially avoided by confining the priming mix ture in a copper or nickel-plated primer cup.

tack the brass. This is especially true in cartridge cases of the common bottle-neck varietyfwhere the internal shoulder thereln provided at the neck constitutes a part especially vulnerable to attack by the mercury, rendering the cases unsuitable for reloading due to the resulting cracked and deteriorated brass.

, In the manufacture of cartridges of the rim-fire type the deleterious efi'ect of the mercury on brass is ofspecial significance, for in this type of cartridge, owing to the intimate contact of the primer charge, not with a separate primer cup but with the cartridge case itself, the use of brass cases with mercury fulminate mixtures is prohibited. It has here been necessary, to use a material in the cases which is immune to the ravages of mercury, and .copper, being a material which qualifies in this regard, has been universally used in cartridge cases for rim-fire ammunition. The desirability and need for substituting brass for the copper in the cases of rim-fire cartridges has. long been felt. For this use, brass possesses many advantages over copper, important among which is its superior strength. This is significant especially in connection with the popular .22 calibre ammunition, where, be-

I cause of the restriction to the use of copper in the cases, allowable pressures and conse quent velocities of the bullets have been required to be kept comparatively low, owing to the unreliability of copper, of a thickness which will efiectively transmit the blow of the firing pin,'to withstand greater pressures. consequently power and penetration in this type ammunition have been heretofore kept down to undesirably low limits.

The present invention has for its object the production of a primin mixture that has no detrimental effect on rass and which may therefore be used in brass cartridge cases and primer cups Without harmful effects.

A further object lies in the production of a priming mixture which besides being nonmercuric is additionally non-corrosive, that is, will leave no corrosive residue .in the 1barrel of the firearm after firing.

A still further object lies in the provision of a priming mixture which is especially suited for rim-fire cartridges, and capable of use in brass cases for such cartridges.

These and further ob'ects are attained by the invention hereina ter more fully described. I

A consideration in connection with the use of brass in rim-firecartridge cases lies in the differences in the physical properties of brass'from those of the.;copper heretofore used; Copper, being quite soft, is readily deformed by the impact of an ordinary firing pin. Brass, being considerably hard-.

- er than copper, shows less local deformation under such impact. Tests, made in the course of experiments leading to the present For this reason muzzle velocities and invention, have revealed the surprising fact that in spite of these differences in properties brass is not only as effective but is even superior to copper in transmitting an ignitlon producing shock from a firing pin to the priming mixture.

In recent years non-mercuric explos1ve substances have been discovered which may be successfully used as an ingredient in replacing mercury fulminate in priming IIllX- tures. The substances known as tetracenes, being non-mercuric, are suitable for use 1n contact With brass.

The present invention embodies the discovery that the many requirements and difiiculties hereinbefore discussed may be satisfied and overcome by the use in a priming mixture comprising a tetracene, such as guanylnitrosaminoguanyltetracene (C H ON of a non-corrosive oxidizing salt, preferably a nitrate such as' lead nitrate. The more important tetracene priming mixtures usually include such a substance as a salt of styphnic acid, such as normal lead styphnate,

usually called lead trinitroresorcinate (C H(NO O Pb) An admixture of these materials performs the combustion initiating function of mercury fulminate with singular effectiveness and is entirely free of the aforementioned disadvantages of mercury fulminate. It does not attack metals or alloys including brass and does not deteriorate when stored for long periods under conditions of high humidity. Moreover, it has been found to be especially adapted for use with lead nitrate as an oxidizer, mixtures including these materials with lead nitrate possessing excellent priming capacity and sensitiveness, and exhibiting remarkable stability under storage. Lead nitrate has already been proposedas a priming mixture oxidizer and has een known to be superior in many respects to the more commonly used non-corrosive oxidizers, such as barium nitrate, but on account of characteristic peculiarities, not fully understood, it has not gained extensive commercial use. The presentinvention includes the discovery that in conjunction with the aforementioned sensitizing ingredients lead nitrate is entirely free from the undesirable peculiarities that have handicapped its commercialization.

The mixturesmay' contain one or more of the usual fuel ingredients, and in the case of rim-fire mixtures an abrasive may also be included. One aspect of the invention relates to increasing the velocity and power of small calibre rim-fire cartridges, and many thousand such cartridges have been loaded to velocities in excess of 1200 feet per second in brass shells, stored without deterioration, and shot without misfires or burst heads.

should be borne in mind that the rim of a rim-fire shell, which is in immediate contact with the priming mixture, is the part of. the

' shell most liable to rupture, since in the chammaterials such as barium nitrate.

ber of a gun in firing condition ithas little or no support. This consideration emphasizes the necessity for keeping the shell rim sound and strong, and the advantage of providing in the rim a mixture which positively does notatt-ack the shell metal.

Typical rim-fire mixtures are as follows:

' Per Prefcent crably Guanylnitrosaminoguanyltetra cene 1- 5 2 Lead trinitroresorcinate 30-50 40 Lead nitrate 25-40 30 Lead sulphocyanate 5-15 8 Glass 10-20 20 The stability of mixtures of this type. when compared with either prior lead nitrate or mixtures containing mercury fulminate. was so extraordinary that the subject was specially investigated, with surprising results. It appears that certain reactions may take place within the mixture. especially in the presence of moisture, which reactions. while in a measure altering the nature of the ingredients, result in the production of substances which are equally or more efficient for priming purposes than the reacting materials. The first of these reactions is an alteration in the structure of the sensitizing ingredient, guanylnitrosaminoguanyltetracene, which is occasioned by the presence of lead nitrate. Lead nitrate renders the mixture acidic in character, and the transformation of guanylnitrosalninoguanyltetracene does not take place in the presence of basic In the presence of lead nitrateguanylnitrosaminoguanyltetracene is transformed into a substance which is easily distinguished by its crystal structure. is more explosive, more sensitive to percussion, and possesses a strong tendency to form salts. It may be called a diazo-hydrate form. or guanyldiazohydrateguanyltetracene', and its probable structure is asfollows:

NH H H 1 1u n The greater explosiveness of this substance as compared with guanylnitrosaminoguanyltetracene may be explained by the presence of two double bonds between nitrogen atoms in the chain as against one such double bond in guanylnitrosaminoguanyltetracene. The relatively great tendency to form salts is apparently due to the presence of the OH group, there being no such group in the ac cepted formula for guanylnitrosaminogua nyltetracene.

The second reaction is one wh ich results in an alteration in the compositioi and crystalline structure of lead sulphocyanate.

It is a. stable crystalline. material which is highly efficient as a primer fuel.

There is also reason to believe that a double salt is formed by a reaction between lead trinitroresorcinate and lead sulphocyanate, although to date this has not been fully established.

It will be seen that both of the foregoing reactions tend. to increase. rather than decrease, the effectiveness of the mixture, and their occurrence may be taken as explaining the efliciency of these mixtures after long storage under adverse conditions of heat and humidity.

Another striking and unusual property of this mixture is its ability to set into a compact and coherent mass without the addition of any binding ingredient. Hitherto it has invariably been found necessary to add to wet mixtures a binding material, such as gum arabic, gum tragacanth, or preparations thereof. If this was not done, the mixture upon drying would crumble and fall out of the shell rim or primer cup in the handling of primers and primed shells necessary to the completionof cartridge loading operations; or, if the mixture did not-fall out in handling, it would be so loose in the shell rim or primer cup as to be dislodged and displaced by the blow of the firing pin, instead of being ignited. The mixtures of this application have been found to be entirely self-setting. a binder being not only superfluous, but actually undesirable. The full self-cementing effect appears to require the presence of all of the specified active ingredients, although somewhat the same property is exhibited by various sub-combinations of the'ingredients, particularly lead nitrate and lead trinitrorcsorcinate.

The invention likewise contemplates center-fire mixture comprising guanylnitrosamlnoguanyltetracene with lead nitrate, a typical formula being:

It should be noted that-all of these mix-.-

tures are not only free from mercury fulminate. but also from corrosion producing oxidizers, such as potassium chlorate, thus attaining the goal toward which ammunition makers have striven for many years.

anate. a 4. A' priming mixture containing approximately:

- 15 a Per cent Guanylnitrosaminoguanyltetraicene 2 Lead trinitroresorcinate 40 Lead nitrate 30 Lead s 11ph0cyanate 8 -Glass 2O 5. A priming mixture containing" guanylnitrosaminoguanyltetracene, lead trinitroresorcinate, lead nitrate, lead sulphocyanate, and calciumsilicide.

i 6. A priming mixture containing. guanyL nitrosaminoguanyltetracene, lead trinitrore sorcinate, lead nitrate, and calcium silicide.

JAMES E. BURNS. 

